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생물화공 에너지 / 환경 / 용융탄산염 연료전지용 평판형 개질기의 온도와 공간속도에 따른 성능 변화
이상득(Sang Deuk Lee),황인철(In Chul Hwang),이병권(Byung Gwon Lee),서인석(In Seok Seo),임태훈(Tae Hoon Lim),홍성안(Seong Ahn Hong) 한국화학공학회 2000 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.38 No.5
The plate reformer consisting of combustion chamber and reforming chamber, which can be integrated in the MCFC fuel cell system, has been prepared and the performance test was carried out. In order to study the effect of initial temperature and space velocity on the performance of reformer, the temperature profiles were measured and the conversion of hydrogen and methane and the composition of products were analyzed. Upon the operating condition based on fuel cell stack having fuel utilization of 80%, the reformer was able to generate hydrogen for several ㎾ fuel cell stack, maintaining the hydrogen conversion of above 99% and methane conversion of 98%. The temperature profile recorded during the test showed the endotherm representing the operating state of reformer.
박막을 형성한 원통형 덩어리 모델의 다공성 기체확산 전극 유효성인자
노제승,홍성안,서성섭 ( Je Seung Roh,Seong Ahn Hong,Sung Sup Suh ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.5
The porous gas diffusion electrode was described by cylindrical agglomerate model with electrolyte thin film to investigate the effectiveness factor. System variables such as reaction rate constant, diffusion coefficients, conductivity, agglomerate size, electrode thickness and temperature were combined into four dimensionless parameters. The effectiveness factor was slightly larger than that for slab agglomerate model. However, the effects of the system variables on the effectiveness factor were similar. The effect of electrolyte thin film was very small where the ratio of the thin film thickness to the agglomerate size was less than 0.01. The electrode thickness for the optimum electrode performance was independent of the agglomerate shape.
윤성필,한종희,남석우,임태훈,홍성안,현상훈,유영성,Yoon Sung Pil,Han Jonghee,Nam Suk Woo,Lim Tae-Hoon,Hong Seong-Ahn,Hyun Sang-Hoon,Yoo Young-Sung 한국전기화학회 2001 한국전기화학회지 Vol.4 No.2
기체/전해질/LSM $(La_{0.85}Sr_{0.15}MnO_3)$ 공기극이 만나는 삼상계면 (triple phase boundary) 주위에 YSZ ($8mol\%$ yttria stabilized zirconia) 코팅막 (coating film) 을 형성하여 추가로 삼상계면을 크게 늘린 새로운 전극 미세구조를 갖는 복합 공기극 (composite cathode) 을 개발하였다. 이 복합 공기극을 전해질 두께가 약 $30{\mu}m$인 연료극 (anode)v 지지체 위에 형성하여 $700\~800{\circ}C$의 온도에서 전류전압 특성 및 교류 임피던스 분석을 실시하였다. $800^{\circ}$, 공기 및 수소 조건에서 교류 임피던스 분석 결과 1000Hz주파수 영역을 대변하는 저항성분 R1은 연료극 분극 저항에 해당하였고 100Hz주파수 영역의 저항성분 R2는 공기극 분극 저항 성분, 그리고 10Hz이하 영역의 저항성분 R3는 전극을 통한 기체확산 저항성분으로 특히, 작동 조건인 공기 및 수소 분위기에서는 연료극 쪽 반응기체에 의한 기체확산 저항 성분임을 알 수 있었다. 전지성능 측정 결과 이 복합 공기극을 장착한 전지는 $800^{\circ}C$, 공기 및 산소 조건에서 각각 $0.55W/cm^2$ $1W/cm^2$의 높은 전지성능을 나타내었다. 전류전압 곡선은 기울기가 다른 두 구간으로 구분되었으며, 낮은 전류밀도 하에서 보이는 급격한 전압감소 구간은 공기극 분극저항이 주된 성능 저하의 원인인 반면, 높은 전류밀도 하에서 나타나는 완만한 전압 감소 구간은 전해질에 관련된 분극저항이 주된 성능 저하의 원인이었다. YSZ ($8mol\%$ yttria-stabilized zirconia)-modified LSM $(La_{0.85}Sr_{0.15}MnO_3)$ composite cathodes were fabricated by formation of YSZ film on triple phase boundary (TPB) of LSM/YSZ/gas. The YSZ coating film greatly enlarged electrochemical reaction sites from the increase of additional TPB. The composite cathode was formed on thin YSZ electrolyte (about 30 Um thickness) supported on an anode and then I-V characterization and AC impedance analyses were performed at temperature between $700^{\circ}C\;and\;800^{\circ}C$. As results of the impedance analysis on the cell at $800^{\circ}C$ with humidified hydrogen as the fuel and air as the oxidant, R1 around the frequency of 1000 Hz represents the anode Polarization. R2 around the frequency of 100Hz indicates the cathode polarization, and R3 below the frequency of 10 Hz is the resistance of gas phase diffusion through the anode. The cell with the composite cathode produced power density of $0.55\;W/cm^2\;and\;1W/cm^2$ at air and oxygen atmosphere, respectively. The I-V curve could be divided into two parts showing distinctive behavior. At low current density region (part I) the performance decreased steeply and at high current density region (part II) the performance decreased gradually. At the part I the performance decrease was especially resulted from the large cathode polarization, while at the part H the performance decrease related to the electrolyte polarization.
서성섭,노제승,주재백,남석우,임태훈,오인환,홍성안 ( Sung Sup Suh,Je Seung Roh,Jeh Beck Ju,Suk Woo Nam,Tae Hoon Lim,In Hwan Oh,Seong Ahn Hong ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.5
Effectiveness factor which was defined as the ratio of the current produced by the electrode under diffusional resistance to that produced by the electrode without diffusional resistance was investigated for porous gas diffusion electrode described by agglomerate model. System variables including reaction rate, diffusion coefficient, and agglomerate size were combined into three dimensionless parameters, and their effects on effectiveness factor were studied. Effectiveness factor reaches a maximum value with a critical electrode thickness.
세리아가 첨가된 니켈/칼슘 하이드록시 아파타이트 촉매 상의 부탄 부분산화 연구
곽정훈(Kwak, Jung-Hun),이상엽(Lee, Sang-Yup),김미소(Kim, Mi-So),남석우(Nam, Suk-Woo),임태훈(Lim, Tae-Hoon),홍성안(Hong, Seong-Ahn),윤기준(Yoon, Ki-June) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
Partail oxidation(POX) of n-butane was investigated in this research by employing ceria-promoted Ni/calcium hydroxyapatite catalysts (Ce_xNi_{2.5}Ca_{10}(OH)₂(PO₄)<sub>6</sub> ; x = 0.1{sim}0.3) which had recently been reported to exhibit good catalytic performance in POX of methane and propane. The experiments were carried out with changing ceria content, O₂/n-C₄H_{10} ratio and temperature. As the O₂/n-C₄H_{10} feed ratio increased up to 2.75, n-C₄H_{10} conversion and H₂ yield increased and the selectivity of methane and other hydrocarbons decreased. But with O₂/n-C₄H_{10} = 3.0, n-C₄H_{10} conversion and H₂ yield decreased. This is considered due to that too much oxygen may inhibit the reduction of Ni or induce the oxidation of Ni, which results in poor catalytic activity. The optimum O₂/n-C₄H_{10} ratio lay between 2.50 and 2.75. Ce_{0.1}Ni_{2.5}Ca_{10}(OH)₂(PO₄)<sub>6</sub> showed the highest n-C₄H_{10} conversion and H-2 yield on the whole. In durability tests, higher hydrogen yield and better catalyst stability were obtained with the O₂/n-C₄H_{10} ratio of 2.75 than with the ratio of 2.5.